Don't clear complex objects using memset()

This is fine for simple structs but not class based objects.

win/rfb_win32/DIBSectionBuffer.cxx

 
 DIBSectionBuffer::DIBSectionBuffer(HWND window_)
   : bitmap(0), window(window_), device(0) {
-  memset(&format, 0, sizeof(format));
 }
 
 DIBSectionBuffer::DIBSectionBuffer(HDC device_)
   : bitmap(0), window(0), device(device_) {
-  memset(&format, 0, sizeof(format));
 }
 
 DIBSectionBuffer::~DIBSectionBuffer() {

win/rfb_win32/MonitorInfo.cxx

 static LogWriter vlog("MonitorInfo");
 
 
-static void fillMonitorInfo(HMONITOR monitor, MonitorInfo* mi) {
+static void fillMonitorInfo(HMONITOR monitor, MONITORINFOEXA* mi) {
   vlog.debug("monitor=%p", monitor);
   memset(mi, 0, sizeof(MONITORINFOEXA));
   mi->cbSize = sizeof(MONITORINFOEXA);
 
 
 struct monitorByNameData {
-  MonitorInfo* info;
+  MONITORINFOEXA* info;
   const char* monitorName;
 };